<!DOCTYPE HTML>
<html>
<body>
<div style="opacity:0.8; background-color: gray;">
  <div style="overflow: hidden; -moz-transform: translate(0,10px);">
    <canvas id="canvas" width="256" height="256"></canvas>
  </div>
</div>
<script>
var ctx = document.getElementById("canvas").getContext("2d");
ctx.fillStyle = "yellow";
ctx.fillRect(0, 0, 256, 50);
ctx.fillStyle = "lime";
ctx.fillRect(0, 50, 256, 206);
</script>
</body>
</html>
